1. Field of the Invention
The present invention relates to an apparatus and a method for transferring a material loader such as a wafer carrier. More particularly, the present invention relates to a material loader transferring apparatus having an image recognition device capable of recognizing both a vision mark for correcting the position of a robot arm and a bar code of a material loader to be transferred, instead of having a separate device for bar code recognition. The present invention also relates to a method for transferring the material loader using the material loader transferring apparatus.
2. Background of the Related Art
Generally, a semiconductor fabrication line includes operation areas such as bays, rooms and the like organized for efficiency of operation. For example, predetermined processes are carried out in semiconductor fabrication equipment installed in the bays. Wafer carriers have generally been transferred from bay to bay by operators. However, the semiconductor chips contained in the wafer carriers may be contaminated during the transfer, by particles generated by the operators. Therefore, automated wafer carrier transfer has been developed to minimize such contamination. Automated wafer carrier transfer is carried out in such a manner that the wafer carrier is removed from a stocker and transferred to the relevant equipment by a wafer carrier transferring apparatus.
More particularly, when the wafer carrier is removed from the stocker, an identifying bar code is attached to the wafer carrier. A bar code recognition device reads the bar code and transmits the information into a host computer. The host computer transmits the information to the relevant equipment.
Thereafter, the wafer carrier is loaded onto the wafer carrier transferring apparatus. The wafer carrier transferring apparatus is moved along a preset conveying line. When the wafer carrier transferring apparatus arrives in front of the relevant equipment, an image recognition device installed in the wafer carrier transferring apparatus recognizes a vision mark for position correction attached to the equipment, the position of a robot arm is corrected and the wafer carrier is loaded onto the equipment by the robot arm. The equipment then checks the identifying information of the wafer carrier which was transmitted from the host computer and performs the relevant process.
However, such a method for transferring the wafer carrier suffers from an operation failure caused when the identifying information of the wafer carrier cannot be checked because the wafer carrier is accidently loaded onto an incorrect process equipment due to system error.
To overcome this disadvantage, a bar code recognition device for reading the bar code on the wafer carrier has been provided in the process equipment. When the bar code recognition device installed in the process equipment reads the bar code on the wafer carrier loaded on a loader of the process equipment, the bar code identifying information is inputted into a controlling portion of the process equipment. The controlling portion checks whether or not the inputted bar code information is the same as the bar code information transmitted from the host computer. If the inputted bar code information is the same as the bar code information transmitted from the host computer, the process is carried out.
However, installation of bar code recognition devices into each piece of process equipment is costly. Moreover, operation of the process equipment must be stopped in order to install the bar code recognition device therein, so productivity suffers.